This invention relates to a fuel injection system for a two cycle engine and more particularly to an improved arrangement for controlling the fuel injection of such an engine.
It is known that the fuel requirements of a crankcase compression two cycle internal combustion engine can be easily determined by sensing the pressure in the crankcase chamber. Therefore, a variety of fuel injection systems for such engines have been proposed that embody a pressure sensor mounted in the crankcase chamber of the engine and which provides a pressure signal to a controller which then controls the amount and timing of fuel injection. Although such systems are extremely effective, there are some problems attendant with them.
Specifically, when the sensor is mounted directly in the wall of the crankcase chamber, it tends to become heated due to the heat transmitted to it through the engine wall construction. As is well known, not only fuel is present in the crankcase chamber, but also lubricant can be present there. This lubricant may either be mixed with the fuel or delivered independently. The fuel and lubricant tend to accumulate in the crankcase chamber and can become deposited on the pressure sensor. If the pressure sensor becomes heated, however, then the fuel and particularly the oil may clog or solidify on the pressure sensor and adversely effect the pressure signal.
In order to obviate these problems, it has been proposed to remotely position the pressure sensor and to connect it to the crankcase chamber through a small conduit. However, this type of arrangement also has the disadvantage that fuel and lubricant may accumulate in the small conduit. With time, this accumulated fuel and lubricant can solidify and again the pressure signal becomes deteriorated.
It is, therefore, a principal object of this invention to provide an improved arrangement for sensing the pressure in a crankcase chamber of a two cycle engine and for controlling a fuel injector with the sensed pressure.
It is a further object of the invention to provide an arrangement for mounting the pressure sensor so that it will maintain a good signal during extending periods of operation and during extended time periods.
It is a further object of this invention to provide an arrangement for insuring against the accumulation of solidified or congealed fuel and lubricant on the pressure sensor of a two cycle crankcase compression internal combustion engine.